1. Field of the Invention
The present invention relates to an electronic part protecting structure and process for protecting electronic parts such as a liquid crystal display element, a substrate of a drive circuit for driving the liquid crystal display element and a light source of the liquid crystal display element by a pair of cases.
2. Description of the Related Art
A liquid crystal display device includes electronic parts such as a liquid crystal display element, a substrate of a drive circuit for driving the liquid crystal display element and a light source of the liquid crystal display element. The liquid crystal display element, drive circuit substrate and light source are arranged between and protected by a pair of cases when they are used. Thus, the electronic parts are protected from the surrounding circumstance by the cases.
FIG. 13A is an exploded perspective view showing a structure of the liquid crystal display device of a first prior art, and FIG. 13B is a section of the same. One 11 of a pair of cases 11 and 12 for arranging the electronic parts therebetween is made larger than the other 12. In a side face 11a of the case 11, there is formed an opening 13. In a side face 12a of the case 12, there is formed a pawl 14 which is directed outward of the case 12 and given substantially the same height as the depth of the opening 13. The electronic parts, as arranged between the cases 11 and 12, are assembled by covering the case 12 with the case 11 to fit the opening 13 and the pawl 14 to each other.
FIG. 14 is a section showing a structure of the liquid crystal display device of a second prior art. A pair of cases 15 and 16 are fastened and assembled together with electronic parts 18 by tapping screws 17.
In a first structure, the cases 11 and 12 can be opened to extract the electronic parts by forming a gap between the side faces 11a and 12a and can be assembled again to restore with no trace of disassembly. In a second structure, the cases 15 and 16 can also be opened to extract the electronic parts by loosening the tapping screws 17 and can be assembled again to restore with no trace of disassembly. From the liquid crystal display device to be applied to a play machine such as an electronic control type pinball machine and used publicly, therefore, the electronic parts can be extracted and reconstructed so that the liquid crystal display device can be restored without leaving no trace and can be illegally used.
As a countermeasure for preventing the reconstruction of the electronic parts, there is disclosed a device for detecting the opening of cases in Japanese Utility Model Registration No. 3020870. In the technique disclosed, the opening of the cases is electrically detected by a sealing apparatus 1, as shown in FIG. 15. Specifically, this sealing apparatus 1 includes a memory circuit 2, an oscillator 3, a frequency divider 4, a display/output circuit 5 and an erase circuit 6. When the case opening is detected in the memory circuit 2 by a sensor SE, its detection signal is stored in a flip-flop FF. These sensor SE and flip-flop FF are supplied at all times with the supply voltage from an internal power supply C1. As a result, the storing action is continued even if the external power voltage is interrupted. The external power voltage is supplied to activate the oscillator 3, the frequency divider 4 and the display/output circuit 5 thereby to divide a signal SO from the oscillator 3 by the frequency divider 4, to generate a display signal by using frequency dividing signals S1 and S2 and to flash a light emitting diode LED1. The flashing pattern of the light emitting diode LED1 is switched according to the output of the flip-flop FF so that the opening of the cases is quickly reported in terms of the flashing state of the light emitting diode LED1.
In Japanese Unexamined Utility Model Publication JP-U 4-72054(1992), on the other hand, there is disclosed a protective cover mounting structure for protecting a display device in a vehicle. The display device is so buried in the dash board that it can be pulled out. Specifically, a slider 21, as shown in FIG. 16, is buried in the dash board, and the display device is arranged in the slider 21 and pulled out together with the slider 21. In the inner circuit of a protective cover 22 attached to the leading end of the slider 21 for protecting the display of the display device, there is formed a groove 25 which encloses the side face of the slider 21 when attached to the slider 21. A plurality of holes 23 are formed in the leading end of the slider 21. A welded portion 24 is formed by covering the leading end of the slider 21 with the protective cover 22 and by spot-welding the groove portion of the protective cover 22 enclosing the holes 23 from the inside of the slider.
When the opening of the cases is to be electrically detected by the apparatus shown in FIG. 15, the many components including the sensor SE, the flip-flop FF, the internal power supply C1 and the light emitting diode LED1 are required to enlarge and complicate the structure thereby to make it expensive. When the mounting structure shown in FIG. 16 is applied to the structure for protecting the electronic parts, one or both of the cases cannot be reused, if once opened when the electronic parts are defective, to lower the using efficiency of the parts.